a coordinate system is lines of longuitude and latitude that are used in a map to locate something. There is a coordiante in the Equatorial Coordinate System that is like longitude in the Geographical Coordinate System.....what is the coordinate? Celestial Equator?

The equatorial coordinate system is usually called geocentric coordinates, which are declination and hour-angle, and the horizontal system is called altitude and azimuth.

The two coordinate systems are tilted relative to one another by 23.4 degrees, the Earth's axial tilt, in the plane of the local meridian of the observer.

As time passes, in geocentric coordinates the declination stays the same while the hour angle increases at 15 degrees per hour. In the horizontal system both coordinates change, with the altitude increasing from zero as an object rises, then reaches its maximum altitude when due south, and then it gradually sets in the west.

The North Point

Cartesian coordinate system.

The coordinate system can be in any number of dimensions whereas the coordinate plane is a 2-dimensional concept.